Highly electro-conductive B4C–TiB2 composites with three-dimensional interconnected intergranular TiB2 network

To achieve lightweight B4C-based composite ceramics with high electrical conductivities and hardness, B4C–TiB2 ceramics were fabricated by reactive spark plasma sintering (SPS) using B4C, TiC, and amorphous B as raw materials. During the sintering process, fine B4C–TiB2 composite particles are firstly in situ synthesized by the reaction between TiC and B. Then, large raw B4C particles tend to grow at the cost of small B4C particles. Finally, small TiB2 grains surround large B4C grains to create a three-dimensional interconnected intergranular TiB2 network, which is beneficial for an electro-conductive network and greatly improves the conductivity of the ceramics. The effect of the B4C particle size on the mechanical and electrical properties of the ceramics was investigated. When the particle size of initial B4C powders is 10.29 µm, the obtained B4C–15 vol% TiB2 composite ceramics exhibit an electrical conductivity as high as 2.79×104 S/m and a density as low as 2.782 g/cm3, together with excellent mechanical properties including flexural strength, Vickers hardness (HV), and fracture toughness (KIC) of 676 MPa, 28.89 GPa, and 5.28 MPa·m1/2, respectively.